LetsEncrypt Express

Free SSL and managed or automatic HTTPS for node.js with Express, Koa, Connect, and other middleware systems.

Install

npm install --save letsencrypt-express

Usage

Minimal

'use strict';

// Note: using staging server url, remove .testing() for production
var lex = require('letsencrypt-express').testing();

var express = require('express');
var app = express();


// A happy little express app
app.use(function (req, res) {
  res.send({ success: true });
});


// assumes ~/letsencrypt/etc as the configDir and ports 80, 443, and 5001 by default
lex.create(app).listen();

How Automatic?

Extremely.

• renewals are fully automatic and happen in the background, with no downtime
• registrations are automatic in testing, but require a approval callback in production

testing mode

All you have to do is start the webserver and then visit it at it's domain name. The certificate will be retrieved automatically. Renewals and Registrations are automatic.

production mode

You can run registration manually:

npm install -g letsencrypt-cli

letsencrypt certonly --standalone \
  --config-dir ~/letsencrypt/etc \
  --agree-tos --domains example.com --email user@example.com

(note that the --webrootPath option is also available if you don't want to shut down your webserver to get the cert)

Or you can approve registrations with the opts.approveRegistration(domain, cb)callback:

{ configDir: '...'
// ...
, approveRegistration: function (hostname, cb) {
    // check a database or something, get the user
    // show them the agreement that you've already downloaded
    cb(null, {
      domains: [hostname]
    , email: 'user@example.com'
    , agreeTos: true
    });
  }
}

(if you don't check and simply complete the callback, an attacker will spoof SNI packets with bad hostnames and that will cause you to be rate-limited and or blocked from the ACME server)

Examples

Use with raw http / https modules

Let's say you want to redirect all http to https.

var LEX = require('letsencrypt-express');
var http = require('http');
var https = require('http2');
// NOTE: you could use the old https module if for some reason you don't want to support modern browsers

var lex = LEX.create({
  configDir: __dirname + '/letsencrypt.config'
, approveRegistration: function (hostname, cb) {
    cb(null, {
      domains: [hostname]
    , email: 'CHANGE_ME' // 'user@example.com'
    , agreeTos: true
    });
  }
});

function redirectHttp() {
  http.createServer(LEX.createAcmeResponder(lex, function redirectHttps(req, res) {
    res.setHeader('Location', 'https://' + req.headers.host + req.url);
    res.end('<!-- Hello Developer Person! Please use HTTPS instead -->');
  })).listen(80);
}

function serveHttps() {
  var app = require('express')();
  
  app.use('/', function (req, res) {
    res.end('Hello!');
  });
  
  https.createServer(lex.httpsOptions, LEX.createAcmeResponder(lex, app)).listen(443);
}

redirectHttp();
serveHttps();

In short these are the only functions you need to be aware of:

• LEX.create(opts)
  • { configDir: pathname, approveRegistration: func }
• LEX.createAcmeResponder(lex, onRequest)

< 140 Characters

Let's Encrypt in 128 characters, with spaces!

node -e 'require("letsencrypt-express").testing().create( require("express")().use(function (_, r) { r.end("Hi!") }) ).listen()'

More realistic

'use strict';

// Note: using staging server url, remove .testing() for production
var LEX = require('letsencrypt-express').testing();
var express = require('express');
var app = express();

app.use('/', function (req, res) {
  res.send({ success: true });
});

LEX.create({
  configDir: './letsencrypt.config'                 // ~/letsencrypt, /etc/letsencrypt, whatever you want

, onRequest: app                                    // your express app (or plain node http app)

, letsencrypt: null                                 // you can provide you own instance of letsencrypt
                                                    // if you need to configure it (with an agreeToTerms
                                                    // callback, for example)

, approveRegistration: function (hostname, cb) {    // PRODUCTION MODE needs this function, but only if you want
                                                    // automatic registration (usually not necessary)
                                                    // renewals for registered domains will still be automatic
    cb(null, {
      domains: [hostname]
    , email: 'user@example.com'
    , agreeTos: true              // you
    });
  }
}).listen([80], [443, 5001], function () {
  console.log("ENCRYPT __ALL__ THE DOMAINS!");
});

Using with Koa

'use strict';

// Note: using staging server url, remove .testing() for production
var lex = require('letsencrypt-express').testing();
var koa = require('koa');
var app = koa();


app.use(function *(){
  this.body = 'Hello World';
});

lex.create({
  configDir: './letsencrypt.config'                 // ~/letsencrypt, /etc/letsencrypt, whatever you want

, onRequest: app.callback()                         // your koa app callback

, letsencrypt: null                                 // you can provide you own instance of letsencrypt
                                                    // if you need to configure it (with an agreeToTerms
                                                    // callback, for example)

, approveRegistration: function (hostname, cb) {    // PRODUCTION MODE needs this function, but only if you want
                                                    // automatic registration (usually not necessary)
                                                    // renewals for registered domains will still be automatic
    cb(null, {
      domains: [hostname]
    , email: 'user@example.com'
    , agreeTos: true              // you
    });
  }
}).listen([], [4443], function () {
  var server = this;
  var protocol = ('requestCert' in server) ? 'https': 'http';
  console.log("Listening at " + protocol + '://localhost:' + this.address().port);
});

More Options Exposed

'use strict';

var lex = require('letsencrypt-express');
var express = require('express');
var app = express();

app.use('/', function (req, res) {
  res.send({ success: true });
});

var results = lex.create({
  configDir: '/etc/letsencrypt'
, onRequest: app
, server: require('letsencrypt').productionServerUrl
}).listen(

  // you can give just the port, or expand out to the full options
  [80, { port: 8080, address: 'localhost', onListening: function () { console.log('http://localhost'); } }]

  // you can give just the port, or expand out to the full options
, [443, 5001, { port: 8443, address: 'localhost' }]

  // this is pretty much the default onListening handler
, function onListening() {
    var server = this;
    var protocol = ('requestCert' in server) ? 'https': 'http';
    console.log("Listening at " + protocol + '://localhost:' + this.address().port);
  }
);

// In case you need access to the raw servers (i.e. using websockets)
console.log(results.plainServers);
console.log(results.tlsServers);

WebSockets with Let's Encrypt

Note: you don't need to create websockets for the plain ports.

var WebSocketServer = require('ws').Server;

results.tlsServers.forEach(function (server) {
  var wss = new WebSocketServer({ server: server });
  wss.on('connection', onConnection);
});

function onConnection(ws) {
  var location = url.parse(ws.upgradeReq.url, true);
  // you might use location.query.access_token to authenticate or share sessions
  // or ws.upgradeReq.headers.cookie (see http://stackoverflow.com/a/16395220/151312)

  ws.on('message', function incoming(message) {
    console.log('received: %s', message);
  });

  ws.send('something');
}

API

                                // checks options and sets up defaults. returns object with `listen`
LEX.create(options)             // (it was really just done this way to appeal to what people are used to seeing)

  lex.listen(plain, tls, fn)    // actually creates the servers and causes them to listen


                                // receives an instance of letsencrypt, returns an SNICallback handler for https.createServer()
LEX.createSniCallback(opts)     // this will call letsencrypt.renew and letsencrypt.register as appropriate
                                // it will randomly stagger renewals such that they don't all happen at once on boot
                                // or at any other time. registrations will be handled as per `handleRegistration`
  opts = {
    letsencrypt: <obj>          // letsencrypt instance
  , memorizeFor: <1 day>        // how long to wait before checking the disk for updated certificates
  , renewWithin: <3 days>       // the first possible moment the certificate staggering should begin
  , failedWait:  <5 minutes>    // how long to wait before trying again if the certificate registration failed


                                // registrations are NOT approved automatically by default due to security concerns
  , approveRegistration: func   // (someone can spoof servername indication to your server and cause you to be rate-limited)
                                // but you can implement handling of them if you wish
                                // (note that you should probably call the callback immediately with a tlsContext)
                                //
                                // default    function (hostname, cb) { cb(null, null); }
                                //
                                // example    function (hostname, cb) {
                                //              cb(null, { domains: [hostname], agreeTos: true, email: 'user@example.com' });
                                //            }


  , handleRenewFailure: func    // renewals are automatic, but sometimes they may fail. If that happens, you should handle it
                                // (note that renewals happen in the background)
                                //
                                // default    function (err, letsencrypt, hostname, certInfo) {}
  }


                                // uses `opts.webrootPath` to read from the filesystem
LEX.getChallenge(opts, hostname, key cb)

LEX.createAcmeResponder(opts, fn)  // this will return the necessary request handler for /.well-known/acme-challenges
                                   // which then calls `fn` (such as express app) to complete the request
                                   //
                                   // opts     lex instance created with LEX.create(opts)
                                   //         more generally, any object with a compatible `getChallenge` will work:
                                   //         `lex.getChallenge(opts, domain, key, function (err, val) {})`
                                   //
                                   // fn       function (req, res) {
                                   //            console.log(req.method, req.url);
                                   //
                                   //            res.end('Hello!');
                                   //          }

Options

If any of these values are undefined or null the will assume use reasonable defaults.

Partially defined values will be merged with the defaults.

Setting the value to false will, in many cases (as documented), disable the defaults.

configDir: string               // string     the letsencrypt configuration path (de facto /etc/letsencrypt)
                                //
                                // default    os.homedir() + '/letsencrypt/etc'


webrootPath: string             // string     a path to a folder where temporary challenge files will be stored and read
                                //
                                // default    os.tmpdir() + '/acme-challenge'


getChallenge: func | false      // false      do not handle getChallenge
                                //
                                // func       Example:
                                //
                                // default    function (defaults, hostname, key, cb) {
                                //              var filename = path.join(defaults.webrootPath.replace(':hostname', hostname), key);
                                //              fs.readFile(filename, 'ascii', function (cb, text) {
                                //                cb(null, text);
                                //              })
                                //            }


httpsOptions: object            // object     will be merged with internal defaults and passed to https.createServer()
                                //            { pfx, key, cert, passphrase, ca, ciphers, rejectUnauthorized, secureProtocol }
                                //            See https://nodejs.org/api/https.html
                                //            Note: if SNICallback is specified, it will be run *before*
                                //            the internal SNICallback that manages automated certificates
                                //
                                // default    uses a localhost cert and key to prevent https.createServer() from throwing an error
                                //            and also uses our SNICallback, which manages certificates


sniCallback: func               // func       replace the default sniCallback handler (which manages certificates) with your own


letsencrypt: object             // object     configure the letsencrypt object yourself and pass it in directly
                                //
                                // default    we create the letsencrypt object using parameters you specify

server: url                     // url        use letsencrypt.productionServerUrl (i.e. https://acme-v01.api.letsencrypt.org/directory)
                                //            or letsencrypt.stagingServerUrl     (i.e. https://acme-staging.api.letsencrypt.org/directory)
                                //
                                // default    production

Fullest Example Ever

Here's absolutely every option and function exposed

var http = require('http');
var https = require('https');
var LEX = require('letsencrypt-express');
var LE = require('letsencrypt');
var lex;

lex = LEX.create({
  webrootPath: '/tmp/.well-known/acme-challenge'

, lifetime: 90 * 24 * 60 * 60 * 1000    // expect certificates to last 90 days
, failedWait: 5 * 60 * 1000             // if registering fails wait 5 minutes before trying again
, renewWithin: 3 * 24 * 60 * 60 * 1000  // renew at least 3 days before expiration
, memorizeFor: 1 * 24 * 60 * 60 * 1000  // keep certificates in memory for 1 day

, approveRegistration: function (hostname, cb) {
    cb(null, {
      domains: [hostname]
    , email: 'user@example.com'
    , agreeTos: true
    });
  }

, handleRenewFailure: function (err, hostname, certInfo) {
    console.error("ERROR: Failed to renew domain '", hostname, "':");
    if (err) {
      console.error(err.stack || err);
    }
    if (certInfo) {
      console.error(certInfo);
    }
  }

, letsencrypt: LE.create(
    // options
    { configDir: './letsencrypt.config'
    , manual: true

    , server: LE.productionServerUrl
    , privkeyPath: LE.privkeyPath
    , fullchainPath: LE.fullchainPath
    , certPath: LE.certPath
    , chainPath: LE.chainPath
    , renewalPath: LE.renewalPath
    , accountsDir: LE.accountsDir

    , debug: false
    }

    // handlers
  , { setChallenge: LEX.setChallenge
    , removeChallenge: LEX.removeChallenge
    }
  )

, debug: false
});

http.createServer(LEX.createAcmeResponder(lex, function (req, res) {
  res.setHeader('Location', 'https://' + req.headers.host + req.url);
  res.end('<!-- Hello Mr Developer! Please use HTTPS instead -->');
}));

https.createServer(lex.httpsOptions, LEX.createAcmeResponder(lex, function (req, res) {
  res.end('Hello!');
}));

Heroku?

This doesn't work on heroku because heroku uses a proxy with built-in https (which is a smart thing to do) and besides, they want you to pay big bucks for https. (hopefully not for long?...)